Stereoscopic cinematographic apparatus



April 13,1926.

M.' GIRSDANSKY STEREOSCOPIC CINEMATOGRAPHIC AFPARATQS Filed March 12, 1921 5 Sheets-sheaf. 1

D uf/uDDDDDDuUr OGDDDG DDGD R INVENTUR ATTORNEYS April 13 1926.

M. GIRSDANSKY STERECSCOPIG CINEMATOGRAPHIC APPARATUS Filed March 12,1321 v 5 Sheets-Sheet 2 v mvtpron BY XL A; man E-YHS April 13,1926.

M.--GlR$DAN-SKY STEHEOSCOPIC CINEMATOGRAPHIC APPARATUS 5 Sheets-Shet 5Filed March 12 1921 46; ATTORNEYS April 13, 1926. 1,580,242

M. GIRSDANSKY STEREOSGOPIC CINEMATOGRAPHIC APPARATUS Filed March 12 13215 Sheets-Sheet 4 INVENTOR April 13,1926. 1,580,242

M. GIRSDANSKY STEREOSCOPIC CINEMATOGRAPHIC APPARATUS Filed March 12,1921 5 Sheets-Sheet 5 165w I64 INVENTOR I BY % ATTORNEYS tionul viewtaken 011 the line 11 of Fig. 4.

Patented Apr. 13, 1926.

' UNITED STATES MAXIMILLIAN GIRSDANSKY, OF NEW YORK, N. Y.

STEREOSGOPIG CINEMATOGRAPHIG APPARATUS.

' Application filed March 12, 1921. Serial No. 451,755.

To all 1071 am it may concern:

Be it known that I, MAxiMInnmN Gins- DANSKY, a citizen of the UnitedStates of America, residing at New York, in the county and State of NewYork, have invented certain new and useful Improvements in StereoscopicCinematographic Apparatus, of which the following is a full, clear, andexact description.

This invention relates to cinematography and has for one of itsprincipal objects to provide a method and means whereby images of astationary or moving object may be obtained and projected upon a screento produce stereoscopic pictures.

From a more specific aspect, a further object is to provide a method inwhich the ordinary cameras and projecting apparatus, now well known inthe art, may be employed. by adding certain means hereinafter disclosed.Other objects and advantages will appear upon inspection of thefollowing description.

Referring to the drawings which illustrate what I now consider preferredphysical embodiments for carrying the .invention into practice:

Fig. 1 is a diagrammatic, horizontal see- Fig. l is a view similar toFig. 1 but illustrating aniodification.

Fig. 2 -is a detail view of a cinematographic film showing the relativeposition of alternating in'iages of the same object.

Fig. 3 is a view illustrating the stereoscopic images as they wouldappear when projected upon a screen.

Fig. 4 is a fragmentary VOl'tlCHl'SGCtlOH ot a motion picture cameraembodying one form of retracting means.

Fig. 5 is a fragmentary frontelevation of a motion picture camera orprojecting apparatus embodying a modified and pre ferred form ofrefracting means.

Fig. 6 is a diagrammatic view representing a section taken on the line6-6 of Fig. 5.

Figs. 7 and 8 are views similar to Fig. 6 but illustratingmodifications.

Fig. 9 is a diagrammatic elevation showing how the retracting devicesshown in Fig. 5 may be modified.

Fig. 10 is a view similar to Figs. 6. 7 and i 8 but illustrating afurther modification.

'The invention may be best understood by referring first to Figs. 1, 2and 3. In

Fig. 1 I have diagrammatically indicated a camera comprising the usualfilm gate 11), through which a negative iihn 11 is adapt ed to bepassed, and an Optical system including one or morecamera lenses 12.. lmount in front of the lens 12, a retracting means shown, in this figure,in the form of a prism 13 of glass or other suitable refractivematerial. Assume that it-is dcsiredto produce stereoscopic pictures ofan object 0, located for convenience in illust-ration on the opticalaxis A.A of the camera. F or further convenience assume that the objectO is stationary, .it being understood that the object may be moving. I fthe negative 11 is exposed when the re.- fracting means or prism 13 isin the full. line position, a ray of light passing from the object 0along the optical axis will pass through the prism 13, being bent orrefracted thereby toward the thick edge of the prism, thence through thelens 12 and thence to the negative film 11. where an image of the object0 will be formed at 14. The light is now out off from the negatiie film11 and the latter is shifted one image space, and the prism 13 moved tothe dotted line position. When the film and prism are stationaryexposure again takes place. The image of the object 0 will now beproduced at 15 upon the negative film 11. The light is again cut oilfrom the negative film, the latter shifted one image space, and theprism 13 moved back to its full line position. Exposure then againtakcsplacc, an image of the object O appearing at 14. When the desiredlength of film has been exposed it may be removed from the camera anddeveloped and fixed in any of the well known ways. The negative filmwould then appear as indicated 'diagramimttically in Fig. 2. It. will benoted that, instead of being in vertical alignment, theimages of theobject are displaced alternately to the right and left. For convenienceI shall. refer to one set of alternate images or image spaces at R and.the other series as L. A positive film may now be printed, say bycontact printing, from the negative and the two seriesfof images wouldhear the same relative positions as those shown on the negative in Fig.2. 5

.ln projecting the positive iu'iagcs upon the screen any suitablecinematographic n'o'jector, or projecting apparatus now well knowniirtlie art may be employed by providing certain additional apparatusone form of which I will now describe. For convenience in description itmay be assumed that a projector is} diagrammatically illustrated in Fig.

. 1 (the source of light not being shown). As-

smne that the film 11 is the positive film above referred to, it havingbeen developed and fixed. A prism or other retracting means representedat 13 is employed. This prism is ofsuch degree that when in the fullline position illustrated, and with an image space It (of the positive)in the exposure opening of the film gate, the image will be projectedand appear at R upon the screen 16 (See Fig. 3). The exposure is theninterrupted, the positive film shifted or fed one image space to move animage L into the exposure opening of the film gate,-and the prism 13 ismoved to the dotted line position. Exposure then takes place and theimage L will be projected and appear upon the screen The cycle issuccessively repeated so that images R and L will alternately be shownupon the screen and due to persistence of vision stereoscopic pictureswill result. In other words a stereoscopic, cinematographic picture willappear to those viewing the screen 16, tln'ough any suitable instrumentspreferably of the type disclosed in my copending application Ser. No.339,- 012. Obviously the object 0 may be a moving one as well as astationary one.

I have disclosed above, one method cmbodying my invention and have alsobroadly and generally disclosed one set of instrumentalities forcarrying the method into 'prac tice. I-'shall now describe morespecifically one form of camera for exposing the negatives. Beforeproceeding, it may be stated that. the invention may be practiced withvarious forms of cinematographic cameras embodying dilfering formsoffeed and other mechanisms. Furthermore it is to be understood that Ihave made no atten'ipt to disclos a camera, complete in all its detailsbut only such parts as are necessary to a proper comprehension of thepresent invent ion.

Referring to Fig. 4, the camera 20 is shown as comprising a filmgatelt), adapted to have passed therethrough a film 11, and a lens 12,all of which-will be recognized in view of the description in connectionwith Fig. 1. The prism 13, provided in accordance with my invention,will also bercco,fnized. The -amera 20 is shown provided with the usualshutter 21 to control the exposure of the film 11 and to obscure or outoft the light therefrom while the film is ininotion. Of the varioustypes of filn'l-feeding mechanism I have selected for purposes ofillustration the well known Genevastop' type which may be described asfollows. I

A disk 22 having secured thereto a. pin 24 and cam 23 -is operativelyconnected by means of bevel gears 25, 26, shaft 27 and bevel gears 28,29to a shaft 30 to be driven the general shape of a Maltese crosscooperates with the cam 23 and pin 24 to be inlermittently operatedthereby in the well known manner. The star wheel 32 is secured to ashaft 31 to which there is also secured one or more feed sprockets 33having peripheral teeth adapted to enter the marginal perforations ofthe film to translate or feed the latter. The shutter 21 is shown of thedisk type and secured to a shaft 34 having also secured thereto a bevelgear which meshes with and is driven by the gear 29. Means are providedfor operating the prism 13 automatically and in proper time relationshipwith respect to the shutter 21 and the film feeding mechanism. One formof such.

secured to a shaft 38. The latter is adapted to drive a vertical shaft41, journaled in suitable brackets 42, through bevel gears 39 and 40.The prism 13 is mounted in a frame 43 so connected to the two parts ofthe shaft 41 that theprism may be caused to assume either the full lineor the dotted line position illustrated in Fig. 1. Assuming that theshaft 30 is being actuated continuously, the above described parts aredesigned to operate substantially as follows.

VVith the parts in the position shown in Fig. 4 the film 11 isstationary, the prism 13 is stationary and in the full line positionshown in Fig. 1,'and the shutter 21 is in such position as to expose thenegative 11. The shutter 21 next moves to a position obscuring orcutting off the light from the film and, while the light is so cut oil,the feed mechanism operates to move the film one image space in the filmgate and the shaft 41 and consequently prisn'i 13 is rotated through180. The film is then stationary as is also the prism 13, the latter nowbeing in the dotted line position shown in Fig. 1.'

The shutter 21 now moves again to expose the negative and so on. It willbe noted that the mechanism illustrated in Fig. 4 accomplishesautomatically, simply by rotation of the shaft 30, the series ofoperations apparatusas is necessary for a proper comprehension of thisform of the invention, and additional illustration would constitutesurplusage. Thus it will be apparent to those skilled in the art thatsome suitable form of light source will be employed in the projector andit is unnecessary to illustrate this and other well known auxiliaryapparatus. A

- While the machine shown in Fig. 4 is practically operable it is opento some degree of objection in that the devices 13 and 37 to 41.inclusive are operated intermittently and on high speeds the incidentalshock or succession of shocks may prove damaging to" the prism 13 aswell as tothe parts of the camera proper. To overcome this objection andto effect certain other advantages which will hereinafter appear, I havedevised a form of retracting meanswhich may be continuously operatedinstead of intermittently as in the case of the refracting means 13shown in Fig. 4. In Fig. 5 I have illustrated one form of such means andmeans for automatically operating the same in proper time relationshipwith respect to the shutter and feed mechanism. The instrument-alitiesillustrated in the last mentioned figure may be employed'in connectionwith either a cinematographic camera or with a ciucmatographicprojecting apparatus and Fig. 5 may therefore be taken as illustrativeof both of such applications. However to avoid surplusage in descriptionthe latter will be confined, in its detailed consideration, to-theapplication to a camera. In this form of device the elements 13 and 36to 43 inclusive would be omitted and replaced by the instrumentalitiesdepicted in Fig. 5.

The shutter shaft 34 (see Fig. 5) is prolonged to project beyond thefront wall of the camera 20 and has secured thereto a spur gear 50 whichdrives a spur gear 5 1,secured to a shaft 52, through an idler gear 53.The shaft 52 has also secured thereto a gear 54 which meshes with anddrives both of the relatively large gears 55, 56. The gear 55 is shownrotatably mountedupon a stub shaft 57 and the gear 56 upon a stub shaft58. The last mentioned stub shaft is shown mounted in a bracket 59,secured to the camera 20, in such manner that the gear 56 may be movedin an axial direction toward -or away from the gear 55, fora purposewhich will hereinafter appear. The parts may be held in adjustedposition by means of a set screw 60. Of course, the gear 54 will-be ofsufiicient width to maintain its drive relationship with respect to thegear 56 in any and all of the various positions of axial adjustment ofthe latter.

The gears 55, 56, also constitute frames or supports for the refractingmeans and in the specific form of devices illustrated they are eachconstructed of a rim, a hub and only two diametrically opposed spokesconnecting the rim and hub. Each of the gears or frames 55, 56 carries acorresponding pair of retracting devices 61, 62, 63 and 64 one specificform of which I shall now describe, having reference to Figs. 5 and 6.

The retracting device 61 consists of a sector of a plano-concave lens ofglass or other suitable material, the angle between the bounding radialsurfaces being substantially 180. In other words the device 61 is'a.

solid generated by rotating the section 61 in Fig. 6 about the axis 57through 180. The device 62 is a sector of a plane-convex lens of glassor other suitable refractory material, the angle between the boundingradial surfaces being substantially 180".

The shape of the devices 63, 64 will be ap parent upon inspection ofFig. 6 in view of the foregoing description. Preferably the devices 61,62, 63, 64 should all be of the same diopter. The devices 61, 63 maythen be obtained by cutting a plano-concave lens on a plane through itsoptical axis and the devices 62, 64 may similarly be obtained from aplane-convex lens.

\Vhile the gears 55, 56 rotate through one half rotation about theiraxes 57 and 58 the retracting devices 62, 63 are in the field of thelens 12.(as shown in full lines in Fig. 6) and when the gears turnthrough the next half revolution the refracting devices 62, 63 are movedout of the field of the lens 12 and the devices 61, 64 into the saidfield (as shown in dotted lines in Fig. 6). Comparison of Figs. 1 and 6will indicate that when the devices 62 and 63 are in the field of thelens 12 the same general result is obtained as is the case with theprism 13 in the full line position. And when the devices 61 and 64 arein the field of the lens 12 the same general result is obtained as isthe case with the prism 13 in the dotted line position. Bearing in mindthat the instrumentalities shown in Fig. 5 are to be substituted for theelements 13 and 36 to 43 in the machine shown in Fig. 4, the operationof the invention shown in Figs. 5 and 6 may briefly be described asfollows.

When the devices 61 to 64 are in the relative position shown in Fig. 5,and in full lines in Fig. 6, the shutter 21 isopen and exposure of thefilm 11 is taking place, the

cause of the novel shape of the refracting devices. Exposure having 7been accomplished, the shutter 21 closes and remains closed While thefeed mechanism acts to feed the fihn oneimage' space. vAt. or about thesame time the devices 62, 63 move out of the field of the lens 12 andthe devices 61., 64 move into said'field' Feed movement having beenaccomplished, the shutter 21 again opens to expose the film, the devices61, 64 now being in the field of the lens 12. This cycle is repeateduntil the desired length of The refracting (lev/ices shown in Fig. 6

may assume forms other than those there illustrated. For example thesedevices may be so constructed that they are of prism shape incross-seetion, or each a combined lens and prism, or convexo-concave andconcavo convex or of the double cone or meniscus-prism type, etc. Someof the more numerous possible modifications are illustrated in Figs. 7and 8.

Referring to Fig. 7 a description of one of the devices 61, 62, 63, 64will suffice for all in view of their obvious similarity. The retractingdevice 62 consists of a solid of glass, or other suitable material,generated by. revolving the section 62 (shown in Fig.

7) about the axis 57 and substantially through 180. The result is suchas would be obtained by cutting a right cone (of small altitude ascompared to the diameter of its base) upon a plane through the altitude,the device 62 being one of the two halves so obtained.

' The 'refra-cting devices 61*, 62", 63 and 64" shown in Fig. 8 arecombined lenses and prisms. Each of these devices is a solid obtained byrotating a corresponding one of sections 61", 62*, 68 and 64"substantially through 180 about the respective axes 57, 57, 58 and 58.It will be noted that the devices 61 and 63 if placed thin edge to thinedge, would form a solid, concave on one face and funnel-shaped (i. e.provided with a conical depression) on the opposite face. The devices 62and 64 if placed thick edge to thick edge, would form a solid, convexupon one side and cone-shaped upon the other.

The operation of the devices shown in 'Figs. 7 and 8 wlll'be understoodin view of the foregoing description in connection with Figs. 1, 4, 5and 6. So far as use 111 connection with a cinemato ra )hic camera isconin Fig.' 6 may be resorted to with satisfactory results. Where finestresults of delineation and minutiae are desired the type shown in Fig. 8should be employed.

It will be understood that the dimensions of the various refractingdevices, such as degree and diopter, have been selected primarily forfacility in illustration and the drawings are not intended to be workingdrawings. In general it may be stated that refracting devices ofcomparatively large radial dImODSIOIIS 1' (see Flg. 5) are pref-'erable. The degreeor diopter or both, of the refracting devices.may bedecreased as the radius '1' increases. Without intending to berestricted to any specific dimensions it may be stated that wheredevices of the type illustrated in Fig. 8 are utilized they will givesatisfactory results where the following dimensions are employed: radius(r) 5 inches, prism -1.0 degrees, lens surfaces 0.25 diopter.

Instead of constructing the retracting devices 61 to 64 in the form of180 sectors, smaller angle sectors may be employed. Thus in Fig. 9 Ihave illustrated refracting devices 61 to.64 in the form of quadrants.Of course where sectors other than semicircular ones are employed thegear ratio between shaft 34 and gears 55 and 56' will necessarily bechanged in order to preserve the necessary synchronous relationship ofparts. Thus the devices 61 to 64 shown in, Fig. 9 would rotate only halfas fast as those shown in Fig. 5, assuming the same speed of rotation ofshaft 34 in either case.

Referring back to Fig. 2 it will be seen that the images ofthe object Oupon the series of image spaces R are laterally displaced with respectto those of the series L. If desirable the successive images (assumingthe object to be stationary) may be brought into substantial verticalalignment without impairing the ultimate stereoscopic effect 'byadopting the means diagrammatically indicated in-Fig. 10. In this figurethe film 11, lens 12,:1nd refracting devices 61 to 64 will at once berecognized in view of thedescription in connection with Figs. 1, 4,5'and 7.- A second set of refracting devices 161 to 164 are mounted inand actuated by mechanism such as that show-n in Fig. 5 for the devices61 to 64* except that the former are preferably rotatcd in a directionopposite to the direction of rotation of the latter though at the samespeed. By making the degree of the prisms 161 to 164 the same as that ofprisms 61 to 64, and the ratio (7 :(P::1:10;' (4 being the distancebetween the film and the set of devices 61 to 64 and (P. the distancebetween the two sets of refracting devices) the successive images, uponthe negative film, of a stationary object may be caused substantially toalign each time the film 11 is being fed one image space. The prism andmechanism directly supporting the same acquires considerable momentumduring each movement and the shock on cessation of each movement would'p' rove damaging especailly at high speeds of operation. I have (inconnection with Figs. 5 et seq.) disclosed a preferred structure byvirtue of whichthis objection may be obviated. There are other ways inwhich this objectionable shock or impact action may be considerablyreduced. See for example the arrangement disclosed in Fig.1.

' Here the shaft 41 has secured thereto a substantially cross-shapeframe 43 carrying the four equianguarly spaced prisms 13 to 13 arrangedas illustrated. The gears 39 and 40' are in this case so propertioned asto cause the shaft 41 to rotate 90'each time the film is being fedoneimage space. The operation of this form of the invention will beunderstood in view of the description in connection with Fig.1.

It will be obvious that the shocks incident to 90 rotation arematerially less than in the case of 180 rotation. Furthermore'it will beunderstood that the shocks may be further reduced by employing a stilllarger number of prisms 13*. etc. the gearing 39 and 40 being properldesigned in each case.

In accordance wit the provisions. of the patent statutes, I'have hereindescribedthe principle of operation of my invention, to-

gether with the apparatus. which I now consider to represent the bestembodiment thereof, but I desire to have it understood that theapparatus shown is only illustrative and that the invention can becarried'out by other means. Also, while it is designed to use thevarious features and elements in the combination and relation described,some of these may be altered, others omitted and some of the features ofeach modifi cation embodied in the others Without interfering with themore general results outlined and the invention extends to such use.

The glasses or other refracting devices forming a part of my inventionmay be made achromatic if necessary or esirable.

What 1 claim is 1. The combination with a cinematographic devicecomprising a film gate and intermittent film-feeding mechanism, ofmovably mounted refracting means optically associated with said filmgate, said refracting'means comprising a sector shaped lightretractingdevice one of thefaces of which 0,

is a portion of the lateral surface of a cone,

and means for continuously actuating said.

refracting means in predetermined. timed relationship with respect tosaid'film-feeding mechanism.

2. The combination with a cinematographic device comprising a film gateand intermittent film-feeding mechanism, of

movably mounted refractingmeans optically associated with said filmgate, said refracting means comprising a sector shaped lightrefractingdevice, one of the faces of which is a sector of a lens surface and theother a portion of the lateral surface of a cone, and means forcontinuously actuating said refracting means in predetermined timedrelationship with respect to said film-feeding mechanism.

In testimony whereof I hereto afiix my signature.- a I MAXIMILLIANGIRSDANSKY.

